IP Phone User's Manual

GXV3140 USER MANUAL www.grandstream.com
SOFTWARE VERSION 1.0.0.44 [e-mail]
vocoders are chosen, there could be an audio transmission error.
Preferred Video Coder
Selects the preferred video codec between H.264，H.263 or H.263+. It is
recommended to use H.264
H.264Payload type Selects the dynamic H.264 codec payload type (ranges from 96-127). The
default setting is 99
H.263+ Payload type Selects the H.263+ codec payload type (ranges from 96-127). The default
setting is 103
SRTP Mode Select to Enable SRTP mode. The default is set to Disable.
Silence Suppression This controls the G723/G729 silence suppression/VAD. If set to YES, when no
audio is detected, the phone will send a small number of VAD packets (instead of
audio packets). If Set to NO, this feature is disabled. The default setting is NO.
Voice Frame per TX This configures the number of voice frames transmitted per packet. (It is
recommended to set this based on the Ethernet IS packet limitation – 1500 Byte
or 120kb/s)
When configuring this, it should be noted that the “ptime” value for the SDP will
change with different configurations here. This value is related to the codec used
and the actual frames transmitted during the in payload call.
For example: if the codec is configured to be G.723 and “Voice Frames per TX” is
set to 2. Then in the INVITE request, the “ptime” value for SDP will be 60 ms.
This is because the G723 voice frame is 30 ms. Similarly, if the setting is 2 and
the codec is G729 or G711 or G726, the “ptime” value for SDP in the INVITE
request will be 20 ms.
If the voice frames per TX configuration exceeds the maximum value allowed,
the phone will choose the preferred codec and use the maximum value allowed.
The maximum values: For PCM is 0 frames (x10ms) ; for G76 is 20 frames (x10
ms); for G723 is 32 frames (x30 ms); for G728/G728 is 64 frames (x10ms) and
64 frames (x2.5 ms) respectively.
Adjusting these values will also change the jitter buffer. The phone has an
algorithm for setting the jitter buffer and the jitter buffer rate is around 20-200ms.
For end-users, it is recommended to use the default setting, as incorrect settings
may influence the quality of audio.
G723 Rate This defines the encoding rate for G723 vocoder, and can be 6.3Kb/s or 5.3Kb/s.
Please confirm with your service provider.
Jitter Buffer Type Users can select either Fixed or Adaptive based on network conditions. The
default is Adaptive.